In this task, you're given a question, a context passage, and four options which are terms from the passage. After reading a passage, you will get a brief understanding of the terms. Your job is to determine by searching and reading further information of which term you can answer the question. Indicate your choice as 'a', 'b', 'c', or 'd'. If you think more than one option is plausible, choose the more probable option to help you answer the question.
Q: Question: Was Clagett alive during Dynasty IX? Passage:The ancient Egyptians began dividing the night into  at some time before the compilation of the Dynasty V Pyramid Texts in the 24thcentury. By 2150 (Dynasty IX), diagrams of stars inside Egyptian coffin lids—variously known as "diagonal calendars" or "star clocks"—attest that there were exactly 12 of these. Clagett writes that it is "certain" this duodecimal division of the night followed the adoption of the Egyptian civil calendar, usually placed on the basis of analyses of the Sothic cycle, but a lunar calendar presumably long predated this and also would have had twelve months in each of its years. The coffin diagrams show that the Egyptians took note of the heliacal risings of 36 stars or constellations (now known as "decans"), one for each of the ten-day "weeks" of their civil calendar. (12 sets of alternate "triangle decans" were used for the 5 epagomenal days between years.) Each night, the rising of eleven of these decans were noted, separating the night into twelve divisions whose middle terms would have lasted about 40minutes each. (Another seven stars were noted by the Egyptians during the twilight and predawn periods, although they were not important for the hour divisions.) The original decans used by the Egyptians would have fallen noticeably out of their proper places over a span of several centuries. By the time of (), the priests at Karnak were using water clocks to determine the hours. These were filled to the brim at sunset and the hour determined by comparing the water level against one of its twelve gauges, one for each month of the year. During the New Kingdom, another system of decans was used, made up of 24 stars over the course of the year and 12 within any one night.
 Links: a. Egyptian calendar b. Water clock c. Asterism (astronomy) d. Marshall Clagett
A: 
d